The field of the invention relates to connectors which are capable of forming either a physical or electrical connection between two or more objects. Widely used connection means include a pin and socket connection, a soldered connection, and a nut and bolt connection and a wide variety of crimped connections.
While pin nd socket connections are generally reusable, the strength of the resulting physical or electrical connection is not sufficient to many applications. While a soldered connection typically provides sufficient electrical continuity, it is often not reusable because of its physical location or the heat sensitivity of closely related parts. Nut and bolt connections can come loose and are difficult to use in close quarters. While crimped connections generally have sufficient physical strength, they are usually not reusable. Thus, there is a recognized need for a connector which can form both an excellent electrical as well as a physical connection with another object.
Heat recoverable metals are disclosed in U.S. Pat. Nos. 3,012,882 to Muldawer et al. and 3,174,851 to Buehler et al. and Belgian Pat. No. 703,649 to Wang et al. the disclosures of which are incorporated by reference herein to illuminate the background of the present invention. As made clear in these patents, these alloys undergo a transition between an austenitic state and a martensitic state at certain temperatures. When they are deformed up to 5 to 10 percent while they are in the martensitic state, they will retain this deformation while held in this state but will revert to their original configuration when they are heated to a temperature at which they transform to their austenitic state. This ability to shrink upon warming has been utilized in at least one U.S. patent application to Harrison et al. Ser. No. 51,809 which application is assigned to the assignee of the present application. The disclosure of that application is incorporated by reference herein to illuminate the background of the present invention. The temperatures at which these transitions occur are affected, of course, by the nature of the alloy. A group of alloys having a particularly useful transition temperature is disclosed in another application to Harrison et al. Ser. No. 52,122 which is also assigned to the assignee of the present application and which is also incorporated by reference herein for purposes of background.
While heat recoverable metals have been known for some time, their use in connecting devices has been limited by the relatively small percent deformation they exhibit when they are recovered. The amount of recovery is dependent upon the alloy used as well as the means by which it has been expanded. The recovery is typically limited to 6 to 8 percent of heat recoverable strain. Furthermore, those alloys which exhibit the desired heat recoverability are not necessarily themselves excellent electrical conductors nor do they necessarily exhibit the ability to be readily soldered. Still further, the use of heat recoverable metals often required that the metal be manually forced over a mandrel or other object in order to cause the expansion of the metal.